1. Field of the Invention
The present invention relates to a resistance film type touch panel, and more particularly to a short circuit preventing structure between electrodes in a resistance film type touch panel.
2. Description of the Related Art
A resistance film type touch panel is known in which data is outputted by touching a position on a 2-dimensional coordinates system of the panel. In the touch panel, when the position on the touch panel is touched, an electrode film on an upper side touches an electrode film on a lower side so that an electrically conductive path is formed between the electrode films. The position of the electrically conductive path corresponds to the 2-dimensional coordinates position touched.
FIG. 1 shows a sectional view of the electrode structure on the upper side in the touch panel. A PET layer 102 is formed of PET as a base layer of the upper electrode side. The upper surface of the PET layer 102 is covered by a hard coat layer 101. An anchor layer is formed on the lower surface of the PET layer 102. A transparent electrode film 103 is formed on the anchor layer to oppose to a lower electrode structure. The transparent electrode film 103 in the upper electrode structure is connected with a wiring line 104 in the upper electrode structure through an electric wiring line (not shown). A wiring line 105 in the lower electrode structure is connected with an electrode film (not shown) in the lower electrode structure, and is separated from the wiring line 104 in the upper electrode structure by insulation adhesive 106. Also, the transparent electrode film 103 and the wiring line 104 in the upper electrode structure are separated from the wiring line 105 in the lower electrode structure by a transparent insulation cover resin layer 107.
The PET layer 102 and the transparent insulation cover resin layer 107 have moisture absorption property. An interface between the PET layer 102 and the transparent insulation cover resin layer 107 and between the wiring line 104 in the upper electrode structure and the wiring line 105 in the lower electrode structure tend to collect a water component. When there is ionized material near the interface, the water component changes into electrolysis solution so that there is a possibility that the wiring line 104 in the upper electrode structure and the wiring line 105 in the lower electrode structure form a short circuit. Also, when the wiring line 104 in the upper electrode structure and the wiring line 105 in the lower electrode structure are formed of silver paste, the silver paste dissolves in the water component so that ion migration sometimes occurs.
In conjunction with the above description, a wiring line substrate is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 11-243263). In this reference, a plurality of wiring lines (14) are provided on a base substrate (11) via an adhesive layer (12). That is, the adhesive layer (12) is removed in any region other than the plurality of wiring lines (14). Thus, the adhesive layer (12) which causes ion migration to the surface of the base substrate (11) does not exist between the adjacent wiring lines (14). Therefore, even if a voltage is applied to the wiring line (14), the ion migration never occurs. That is, a short circuit can be prevented between the wiring lines (14).
Also, a taping lead frame is disclosed in Japanese Patent No. 2,928,190. In this reference, an insulating tape is adhered by an adhesive layer to leads of a lead frame which is used for seal of a semiconductor chip. In the taping lead frame having such a structure, a thick portion of the adhesive layer is formed at a position in contact with the lead. The thickness of the thick portion is twice of that of the adhesive layer at a center portion between the leads.
Therefore, an object of the prevent invention is to provide a short circuit preventing structure between electrodes in a resistance film type touch panel, in which a short circuit between both of the electrodes due to moisture can be reliably prevented.
Another object of the present invention is to provide a short circuit preventing structure between electrodes in a resistance film type touch panel, in which dissolving of electrode forming material into moisture and ion migration can be reliably prevented.
In order to achieve an aspect of the present invention, a resistance film type touch panel includes first and second substrates opposing to each other, and respectively having panel planes. A first electrode film is formed in a central portion of the panel plane of the first substrate on a lower surface of the first substrate, and a second electrode film is formed in a central portion of the panel plane of the second substrate on an upper surface of the second substrate. First and second electrodes are connected to the first electrode film and are formed to oppose to each other around the first electrode film on the lower surface of the first substrate. Third and fourth electrodes are connected to the second electrode film and are formed to oppose to each other around the second electrode film on the upper surface of the second substrate orthogonally to the first and second electrodes. First to fourth wiring lines connect the first to fourth electrodes to connection terminals, respectively. An insulating resin film is formed to cover the first and second wiring lines.
Here, each of the first and second wiring lines may be provided to have distances from edges of the first substrate. In this case, the insulating resin film may extend to the edges of the first substrate to cover the first and second wiring lines.
Also, the insulating resin film may be formed to cover the first and second electrodes in addition to the first and second wiring lines. In this case, the insulating resin film may be formed to cover a peripheral portion of the first electrode film in addition to the first and second electrodes.
Also, the fourth electrode may be formed on a lower surface of the insulating resin film directly beneath the first wiring line. Alternatively, the fourth electrode may be formed on a lower surface of the insulating resin film between the first wiring line and an end of the first electrode film.
Also, the first substrate may include a PET layer and an anchor film formed on a lower surface of the PET layer.
Also, the insulating resin film may be transparent.
In order to achieve another aspect of the present invention, a resistance film type touch panel includes first and second substrates opposing to each other, and respectively having panel planes. A first electrode film is formed in a central portion of the panel plane of the first substrate on a lower surface of the first substrate, and a second electrode film is formed in a central portion of the panel plane of the second substrate on an upper surface of the second substrate. First and second electrodes are connected to the first electrode film and are formed to oppose to each other around the first electrode film on the lower surface of the first substrate, and third and fourth electrodes are connected to the second electrode film and formed to oppose to each other around the second electrode film on the upper surface of the second substrate orthogonally to the first and second electrodes. First to fourth wiring lines connect the first to fourth electrodes to connection terminals, respectively. An insulating resin film is formed to cover the first and second electrodes and the first and second wiring lines.
Here, each of the first and second wiring lines may be provided to have distances from edges of the first substrate. In this case, the insulating resin film may extend to the edges of the first substrate to cover the first and second wiring lines.
Also, the insulating resin film may be formed to cover a peripheral portion of the first electrode film in addition to the first and second electrodes.
Also, the fourth electrode may be formed on a lower surface of the insulating resin film directly beneath of the first wiring line. Alternatively, the fourth electrode may be formed on a lower surface of the insulating resin film between the first wiring line and an end of the first electrode film.
Also, the first substrate may include a PET layer and an anchor film formed on a lower surface of the PET layer.
Also, the insulating resin film may be transparent.